Clarification is needed of the possible temporal and pathogenetic relationship of diabetes mellitus to changes in plasma glycoproteins of hepatic origin and renal glomerular microangiopathy. The experimental model of streptozotocin induced diabetes mellitus in the young rat will be used to define the relationship between diabetes and the qualitative and quantitative changes in plasma glycoproteins, as observed in the intact rat and as manifested by the isolated diabetic rat liver perfused for periods of 12 or 24 hours. The methods of single radial immunodiffusion, or radioimmunoassay with antisera to rat fibrinogen, alpha 1-acid glycoprotein (Darcy, Gordon, Miller), alpha 1-acid glycoprotein (Kawasaki), alpha 1-microglobulin, alpha 2-(acute phase) globulin, haptoglobin, C3 component of complement and serum albumin, will be used to measure blood levels of the proteins in the rat, and net biosynthesis of the proteins by the isolated liver. Correlation will also be sought between the duration of the diabetes, blood levels of the specific proteins in the liver donor and net biosynthesis of the glycoproteins by the isolated liver; these data will be related to proteinuria and to histopathologic changes in renal glomerular structure of the diabetic liver donor particularly as they may be illuminated by immunofluorescence microscopy. The perfusion studies will also yield data on the net cumulative utilization of glucose, net disappearance of free amino acid N, net synthesis of urea, and hepatic protein synthesis as estimated by incorporation of L-Leucine-l-14C into liver protein.